// 导出函数
Number.prototype.toFixed = function (d) {
    var s = this + '';
    if (!d) d = 0;
    if (s.indexOf('.') == -1) s += '.';
    s += new Array(d + 1).join('0');
    if (new RegExp('^(-|\\+)?(\\d+(\\.\\d{0,' + (d + 1) + '})?)\\d*$').test(s)) {
        var s = '0' + RegExp.$2, pm = RegExp.$1, a = RegExp.$3.length, b = true;
        if (a == d + 2) {
            a = s.match(/\d/g);
            if (parseInt(a[a.length - 1]) > 4) {
                for (var i = a.length - 2; i >= 0; i--) {
                    a[i] = parseInt(a[i]) + 1;
                    if (a[i] == 10) {
                        a[i] = 0;
                        b = i != 1;
                    } else {
                        break;
                    }
                }
            }
            s = a.join('').replace(new RegExp('(\\d+)(\\d{' + d + '})\\d$'), '$1.$2');

        }
        if (b) s = s.substr(1);
        return (pm + s).replace(/\.$/, '');
    }
    return this + "";
};
